Electric circuit interrupter



April 8, 1947. BENNETT 2,418,690

ELECTRIC CIRCUIT INTERRUPTER Filed July 13, 1944 Figl. 5

llt

I nventor: Robert M. Bennett,

y His Attorney.

Patented Apr. 8, 1947 ELECTRIC CIRCUIT INTERRUPTER Robert M. Bennett,Ithan, Pa., assignor to General Electric Company, a corporation of NewYork Application July 13, 1944, Serial No. 544,705

Claims. 1

My invention relates to electric circuit interrupters and moreparticularly to circuit breakers oi the fluid operated, fluid blasttype.

Circuit interrupters of the fluid operated, fluid blast type have comeinto extensive use during the last few years. Such circuit interruptersoften include serially arranged interrupting contacts and disconnectingcontacts with means for opening the disconnecting contacts only when theinterrupting contacts are open. Such circuit interrupters have requiredcomplicated interlocking means either mechanical, electrical orpneumatic, between the disconnecting contacts and the interruptingcontacts to insure that the interrupting or arcing contacts are in theopen position when the disconnecting contacts are opened. My inventionis concerned with an improved arrangement wherein there is no mechanicalconnection between the disconnecting contacts and the means foroperating the same which is associated with the interrupting contacts,except when the interrupting contacts are in the open position.

It is an object of my invention to provide a new and improved fluidblast circuit interrupter.

It is another object of my invention to provide a circuit interruptingdevice in which the only connection to ground is an air line forsupplying fluid under pressure.

It is another object of my invention to provide a new and improvedcircuit interrupting device employing serially arranged interrupting anddisconnecting contacts in which a lost motion connection insures thatthe interrupting contacts are open before the disconnecting contacts areopen.

It is another object of my invention to provide a new and improved fluidblast circuit interrupter in which the interrupting contacts areoperated during every opening and closing operation, and seriallyarranged disconnecting contacts are opened after one operation of theinterrupting contacts and closed after a successive operation of theinterrupting contacts.

Further objects and advantage of my invention will become apparent asthe following description proceeds and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to and forming a part of this specification.

' For a better understanding of my invention reference may be had to theaccompanying drawing, in which Fig. 1 is a schematic diagram partly insection of a circuit interrupting device embodying my invention shownin'the closedcirouit position.

while Fig. 2 is a partial View of Fig. 1 showing the circuit interrupterin the open non-current carrying position.

For explanatory purposes I have illustrated my invention as applied to acircuit breaker of the cross fluid blast type, such as is disclosed andclaimed in U. S. Letters Patent 2,284,842, Prince et al., granted June2, 1942, and assigned to the same assignee as the present application.As will become apparent from the following description, my invention isparticularly applicable to such a breaker since it eliminates allopenings except the exhaust passage through which flame or are gases mayescape. It will be understood, however, that my invention is equallyapplicable to other types of circuit breakers of the fluid 0peratedtype, which may or may not employ a blast of fluid for are extinguishingpurposes.

For the sake of simplicity and clearness I have illustrated my inventionas applied to a single phase circuit breaker, but it should beunderstood that it would apply equally well to a polyphase circuitbreaker. As illustrated in the drawing, I have disclosed a fluid blast,fluid operated circuit breaker I of the cross gas blast type, comprisinga pair of relatively movable interrupting contacts 2 and 3, and seriallyarranged, relatively movable disconnecting or isolating contacts 4 and5. The relatively separable interrupting contacts 2 and 3 comprise thestationary contact 2 and movable contact 3, arranged to draw an arc inan are extinguishing chamber or are chute 6. The stationary contact 2 isarranged to be connected to a suitable line terminal I and is providedwith spring pressed contact fingers 8 and longer arcing contact fingers9, while movable contact 3 is provided with an arcing tip I0 so thatwhen the contacts separate an arc is drawn between arcing tip l0 andarcing fingers 9. Immediately after separation of the contacts oneterminal of the arc is transferred by a blast of fluid. such as air orother gas issuing from conduit H, which is suitably connected through ablast valve 12 with a source of fluid under pressure l3, from contactfingers 9 to the contact M which is provided with a tip of arc-resistantmetal. The fluid blast from conduit ll during the opening operation ofthe circuit interrupter I drives the arc in the arc chute 8 against theedges of a plurality of partitions l5 which partitions are mounted inthe arc chute B transverse to the arc gap and the ends of which extendclose to the path of movement of arcing tip ID of movable interruptingcontact 3.

In order to produce relative movement between interrupting contacts '2and 3, I provide a fluid motor comprising a cylinder l6 suitablyfastened to are chute G as by fastening means I1. Reciprocatinglymounted within cylinder [8 is a piston 18 directly connected to movableinterrupting contact 3. The working face of piston I8 is exposed to thefluid under pressure admitted to are chute whenever valve [2 is operatedso that not only is reiative separation of contacts 2 and 3 caused butthese contacts are surrounded by a blast of fluid under pressure whichwill extinguish any are drawn. The other side of piston 18 has extendinglerefrom a conducting guide rod 19 which extends outside of cylinder 15.To insure good electrical connection between conducting guide rod i9 andcylinder I provide a plurality of contact fingers 28 mounted on cylinderl6 so as to be in sliding engagement with conducting guide rod IQ. Thefingers 20 or cylinder 16 are electrically connected by means of aconductor 2| with the disconnecting or isolating contacts 4 and 5 to bedescribed hereinafter and under normal conditions conductor 2| is theonly connection of any kind whatsoever between the arcing contacts anddisconnecting contacts of circuit interrupter i. A suitable sp ing 22mounted within cylinder l6 biases interrupting contacts 2 and 3 to theclosed position. It will be obvious then that the interrupting contactsare normally held in the closed position by spring means 22 and areopened only when blast valve I2 is open.

Relatively movable disconnecting contacts 4 and have been illustratedwith the contact 5 as the stationary contact connected to the other lineterminal 23. Disconnecting contact 4 is illustrated as a blade-typemovable contact pivotally mounted at 24 to a stationary support 25, andelectrically connected through conductor 2! with movable arcing contact3. Movable disconnecting contact 4 is normally biased to the openposition by means of a spring 26 and is adapted to be held in the closedposition against the bias of spring 26 by means of a rotatable cam 22',pivotally mounted at 28 to a stationary support 29, which engages acrank 30 rigidly connected to pivotally mounted disconnecting contact 4.When cam 21 is in the position indicated in Fig. 1 disconnecting contact4 is held in the closed position against the force of biasing spring 25.When cam 27 is in the position indicated in Fig. 2 disconnecting contact4 is permitted to move to the open position under the force of spring26.

Rotation of cam 21 to the positions indicated in Figs. 1 and 2, in orderto determine whether the disconnecting contacts 4 and 5 are in theclosed or open position, is obtained by means of a ratchet wheel 3!having a plurality of teeth 32, rotatably mounted with cam 21 aboutpivot 28. Ratchet wheel 3| is illustrated as having four teeth andconsequently is rotated one-quarter revolution by means of a ratchet orpawl 33 associated with the end of guide rod 19 upon each operation ofrelatively movable arcing contacts 2 and It will be observed that thepawl and ratchet wheel arrangement described above is a sort of a lostmotion connection by means of which the desired time delay or sequenceis obtained, insuring that the interrupting contacts are in the openposition before the disconnecting contacts are operated to the openposition. The fluid motor comprising cylinder 15 and piston l8 thereforeoperates both the interrupting contacts and the disconnecting contacts.There is, however, a mechanical connection between the fluid motor andthe disconnecting contacts only at the instant the disconnectingcontacts are operated. At

4 all other times the only connection between the interrupting contactsand the disconnecting contacts is the current path 2| which connectsthem in series.

The operation of the circuit interrupter of my invention will b obviousfrom the detailed description included above. With the circuit breakerin the position indicated in Fig. 1 open operation is accomplishedmerely by opening blast valve l2 which produces relative separation ofinterrupting contacts 2 and 3 and simultaneously a blast of fluid in arcchute 6 to extinguish the arc drawn between contacts 2 and 3. Near theend of the opening stroke of piston i8 pawl 33 engages ratchet wheel 3|rotating it in a clockwise direction as viewed in Fig. l, to theposition indicated in Fig. 2 whereupon spring means 26 causes high speedopening of disconnecting contact 4. As soon as the air is shut off bythe closing of blast valve 12 spring 22 causes the interrupting contacts'2 and 3 to assume the closed position indicated and the breaker remainsin the open position of Fig. 2.

To close the breaker blast opened and the interrupting contacts 2 and 3operate in exactly the same manner as in an opening operation. In thiscase, however, the pawl 33 engages ratchet wheel 31 rotating it in theclockwise direction another quarter of a revolution whereby cam 2'!moves disconnecting contact 4 to the closed position. When valv i2 isagain closed spring 22 will move interrupting contact 3 to the closedposition to complete the circuit between line terminals 1 and 23.

From the above discussion it will be observed that my new and improvedcircuit interrupter comprises a very simple mechanism requiring controlof a single valve for all operations. Every second time that air isadmitted to are chute 6 the disconnecting contacts are closed and forall the other times that blast valve I2 is opened the disconnectingcontacts are opened. The interrupting contacts are the first to openduring a circuit interrupting operation and the last to close during acircuit closing operation. A blast of fluid surrounds the interruptingcontacts during both the circuit closing and circuit opening operation.

t will be apparent to those skilled in the art, that my invention is notlimited to the particular construction shown, but that changes andmodifications may be made without departing from the spirit and scope ofmy invention, and I aim in the appended claims to cover all such changesand modifications.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In an electric circuit breaker, a pair of relatively movableinterrupting contacts, a pair of relatively movable disconnectingcontacts serially arranged with said interrupting contacts, means forcausing relative s aration of interrupting contacts and for siiultanecusiy producing a blast of arc extinguishing fluid ad acent saidinterrupting contacts to extingur'h the are drawn therebetween, andmeans oper csponse to every other operation or" SELiL rrupting contactsfor closing said disconnecting contacts.

2. In an electric circuit breaker, a pair of relatively movableinterrupting contacts, a pair of relatively movable disconnectingcontacts serially arranged with said interrupting contacts, a source of,fiuid under pressure, a fluid motor responsive to the introduction offluid under presvalve i2 is again sure from said source for causingrelative separation of said interrupting contacts, means formechanically connecting said fluid motor to said disconnecting contactsonly when said interrupting contacts are in the open circuit position tocause operation of said disconnecting contacts.

3. In an electric circuit breaker, a pair of relatively movableinterrupting contacts, a pair of relatively movable disconnectingcontacts serially arranged with said interrupting contacts, a source offluid under pressure, a fluid motor, valve means for controlling theflow of fluid from said source to said fluid motor for causing relativeseparation of said interrupting contacts and for simultaneouslyproducing a blast of are extinguishing fluid adjacent said interruptingcontacts to extinguish the are drawn therebetween, means responsive toalternate openings of said valve means for causing opening first of saidinterrupting contacts and then of said disconnecting contacts, and meansresponsive to all other openings of said valve means for causing openingof said interrupting contacts and closing of said disconnectingcontacts.

4. In an electric circuit breaker, a pair of relatively movableinterrupting contacts, a pair of relatively movable disconnectingcontacts serially arranged with said interrupting contacts, a source offluid, a fluid motor responsive to the introduction of fluid underpressure from said source for causing relative separation of saidinterrupting contacts, means for mechanically connecting said fluidmotor to said disconnecting contacts anly when said interruptingcontacts are in the open circuit position to cause opening of saiddisconnecting contacts.

'5. In an electric circuit breaker, a pair of relatively movableinterrupting contacts, a pair of relatively movable disconnectingcontacts serially arranged with said interrupting contacts, a source offluid, a fluid motor responsive to the introduction of fluid underpressure from said source for causing relative separation of said interrupting contacts, means for mechanically connecting said fluid motorto said disconnecting contacts only when said interrupting contacts arein the open circuit position to cause closing of said disconnectingcontacts.

ROBERT M. BENNE'IT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,351,903 Baker et al June 20,1944 990,512 Barnum Apr. 25, 1911 2,287,039 Jansson June 23, 1942

